For conducting a piecing process after an interruption in production or the spinning process, various methods and devices are known in the state of the art. Thus, with many textile machines, it is customary that they are equipped with maintenance devices, movable along the work stations, which carry out all maintenance operations on the spinning units, such as the repair of thread breakages, bobbin changing, rotor cleaning, starting spinning with an empty tube, and the like. For this purpose, the maintenance devices feature a highly complex structure with a variety of different handling elements. Such a spinning machine with a movable maintenance device is described, for example, in DE 198 27 605 A1. However, in the case of multiple spinning units that require maintenance at the same time, considerable delays in the maintenance device may arise. The problem of waiting times is exacerbated by today's increasing trend of textile machines with more and more spinning units.
In order to reduce the waiting times on a movable maintenance device, it has also been known to provide multiple maintenance devices on each side of a spinning machine. DE 101 37 081 A1 describes such a spinning machine. For such machines with multiple maintenance devices, laborious processes for controlling the travel movement of the maintenance devices and the assignment of the individual work stations to the various maintenance devices are required. Nevertheless, when there are multiple spinning units that require maintenance at the same time, waiting times at the maintenance device and thus production losses arise, which reduces the efficiency of the machine.
Therefore, EP 1 283 288 B1 proposes a different approach for maintaining the work stations, with which all handling elements for the piecing of a thread, and possibly additional maintenance elements, are arranged directly at each work station. For this purpose, the work stations of the spinning machine feature individual drives controllable in a defined way, in order to, in a suitable manner, drive the work elements of the spinning unit according to the requirements, both during piecing and upon regular spinning operations. Thus, after production is interrupted, each work station is able to independently piece up the thread. In doing so, the problem of waiting times and the associated loss of production can be avoided. However, such a machine equipped with individual station automation is relatively expensive. In addition, due to the variety of the components to be arranged for each work station, the construction cost is high.
In order to avoid a time-consuming seeking out of a thread end wound on the bobbin and simplify the piecing process, it was further proposed by DE 10 2011 053 811 A1 to, in the event of a foreseeable interruption of the spinning process, shut down the work elements of the individual work stations in a controlled manner. Herein, the conveying speeds of the individual work elements of the spinning machine is reduced to a standstill in a controlled manner, such that a controlled thread breakage arises. Herein, the thread end does not wind on the bobbin; rather, it remains in a defined placing position in the thread path. From there, it can be received directly through handling elements of a movable maintenance device or through handling elements of their own work station and fed to the piecing process.